Anatomy and Physiology - The Tissue Level of Organization

Flashcards covering the key concepts of tissue organization, including types, functions, and classifications.

What is a tissue?

Tissues are groups of cells with a common embryonic origin that function together to carry out specialized activities.

What are the 4 basic tissue types in the human body?

Epithelial, connective, muscular, and nervous.

What is the function of epithelial tissues?

Cover body surfaces, form glands, and line hollow organs, body cavities, and ducts. They are specialized to secrete, filter, and absorb.

What is the function of connective tissues?

Protect, support, and bind organs. Fat stores energy, and blood cells and platelets are types of connective tissue.

What is the function of muscular tissues?

Generate the physical force needed to move body structures and generate heat.

What is the function of nervous tissues?

Detect changes in the body and respond by generating nerve impulses.

From what three primary germ layers do the body's tissues develop from?

Ectoderm, endoderm, and mesoderm.

From which germ layers do each of the four basic tissue types arise?

Epithelial tissues arise from all three germ layers, connective and muscle tissues are derived from mesoderm, and nervous tissue develops from ectoderm.

What are Tight Junctions?

Web-like strands of transmembrane proteins that fuse together the outer surfaces of adjacent cells, creating a leak-proof seal.

What are Adherens Junctions?

Adhesion belts of proteins that attach to microfilaments and keep tissues from separating as they stretch and contract.

What are Desmosomes?

Act as spot welds and use cadherin glycoprotein to hook into the cytoplasm, providing stability to the structure.

What are Hemidesmosomes?

Half-welds that join cells to the basement membrane and not to each other.

What are Gap Junctions?

Pores (Connexons) that allow small substances like ions to pass between cells, enabling rapid spread of nerve or muscle impulses.

How are epithelial tissues classified by arrangement of layers?

Simple (1 layer) and stratified (2 or more layers).

How are epithelial tissues classified by cell shape?

Squamous (thin and flattened), cuboidal (cube-shaped), and columnar (tall and elongated).

What is Simple Squamous Epithelium?

Contains a single layer of flat cells and is found lining the CV and lymphatic systems (endothelium), forming the epithelial layer of serous membranes (mesothelium), and in air sacs of lungs and kidneys.

What is Simple Cuboidal Epithelium?

A single layer of cube-shaped cells that covers the surface of the ovary, lines the anterior surface of the capsule of the eye lens, and lines kidney tubules and small ducts in glands.

What is Non-ciliated Simple Columnar Epithelium?

A single layer of non-ciliated column-like cells with oval nuclei near the base; lines the GI tract, ducts of many glands, and the gall bladder.

What is Ciliated Simple Columnar Epithelium?

A single layer of ciliated column-like cells that lines some bronchioles, uterine tubes, uterus, paranasal sinuses, central canal of spinal cord, and ventricles of brain.

What is Non-ciliated Pseudostratified Columnar Epithelium?

Appears multi-layered but is a single layer of cells attached to the basement membrane. Lines the epididymis, larger ducts of many glands, and parts of the male urethra.

What is Ciliated Pseudostratified Columnar Epithelium?

Appears multi-layered but is a single layer of cells attached to the basement membrane. Lines airways of most upper respiratory tract.

What is Stratified Squamous Epithelium?

Contains two or more layers of cells; keratinized type forms the superficial layer of skin, while nonkeratinized type lines wet surfaces like the mouth and esophagus.

What is Stratified Cuboidal Epithelium?

Has two or more layers of cube-shaped cells; found in ducts of adult sweat glands and part of the male urethra.

What is Stratified Columnar Epithelium?

Basal layers consist of shortened, irregular cells; only the apical layer has columnar cells; lines part of the urethra.

What is Urothelium (Transitional Epithelium)?

Has a variable appearance, allows urinary organs to stretch, and lines the urinary bladder, ureters, and portions of the urethra.

Where do secretions of endocrine glands go?

Enter interstitial fluid and diffuse into the bloodstream without flowing through a duct.

Where do secretions of exocrine glands go?

Enter ducts that empty onto the surface of a covering/lining epithelium, such as the skin surface or the lumen of the stomach.

What are Merocrine glands?

A fluid product released through the cell membrane by exocytosis (e.g., salivary glands).

What are Apocrine glands?

Cellular product and portions of the free ends of glandular cells pinch off during secretion (e.g., mammary glands).

What are Holocrine glands?

Disintegrated entire cells filled with secretory products (e.g., sebaceous glands of the skin).

What are the two basic elements of connective tissue?

Cells and extracellular matrix.

What are the 3 types of fibers found in the extracellular matrix?

Collagen, elastic, and reticular fibers.

What are the classifications of connective tissue?

Loose connective tissue, dense connective tissue, cartilage, bone, and blood.

What are the different types of loose connective tissue?

Areolar, adipose, and reticular.

What types of cells does Adipose tissue contain?

Adipocytes, which store fat in the cytoplasm.

What is the function of Areolar tissue?

Forms thin, delicate membranes and binds skin to underlying tissues.

What is the function of Reticular connective tissue?

Contains thin, reticular fibers and forms a framework for certain internal organs (liver, spleen).

Where is Dense Connective Tissue found?

Tendons, ligaments, deep layer of skin, and the white layer of the eyeball (sclera).

What are the three types of cartilage?

Hyaline, elastic, and fibrocartilage.

What is Hyaline Cartilage?

Contains fine collagen fibers in matrix; found on the ends of bones and supports respiratory structures and passages.

What is Elastic Cartilage?

Contains elastic fibers in a dense network; provides framework for the external ears and parts of the larynx.

What is Fibrocartilage?

Tough tissue containing many collagenous fibers; found in intervertebral discs, knees, and pelvic girdle.

What is the function of Bone (Osseous Tissue)?

Support and protect body structures, form sites for muscle attachments, are sites of blood cell formation, and store and release chemicals.

What are the two types of bone tissue?

Compact and Spongy.

What are bone cells called, and where do they lie?

Osteocytes, lie within lacunae (chambers).

What are the components of Blood?

Blood plasma, red blood cells (erythrocytes), white blood cells (leukocytes), and platelets (thrombocytes).

What are the 3 types of muscle tissue?

Skeletal, cardiac, and smooth muscle.

Where is Skeletal Muscle Tissue located and what is its function?

Attached to bones by tendons and is responsible for motion, posture, heat production, and protection.

Where is Cardiac Muscle Tissue located and what is its function?

Heart wall and pumps blood to all parts of body.

Where is Smooth Muscle Tissue located and what is its function?

Iris of eyes, walls of hollow internal structures (blood vessels, airways to lungs, stomach, intestines, etc.) and is responsible for motion.

What two kinds of cells does Nervous Tissue consist of?

Neurons and neuroglia.

What are the 3 types of Epithelial membranes?

Mucous membranes, serous membranes, and cutaneous membranes.